Apparatus for minimizing the deposition of deleterious compounds in a petroleum fuel fired gas chamber



3,002,345 G THE DEPOSITION OF DELETER IOUS Oct. 3, 1961 w. E. YOUNGAPPARATUS FOR MINIMIZIN COMPOUNDS IN' A PETROLEUM FUEL FIRED GAS CHAMBERFiled Jan. 12, 1960 IN TEGRATING CONTROLLER FIG].

TO THER l/l O COUPLE FUEL CONTROL FIG.4.

INVENTOR WILLIAM E.YOUNG nited States This invention relates to gasturbine power plants generally, more particularly to gas turbine powerplants operating on residual petroleum oil as a fuel and has for anobject to provide an improved method and apparatus for inhibiting theformation of deleterious deposits formed by the combustion gas productson the metallic components of the turbine.

Residual fuel oil is becoming more widely used in the operation ofindustrial gas turbines because of its low cost and high B.t.u. content.However, as well known in the art, residualpetroleum fuel oil containssodium, sulphur and vanadium which form compounds during combustion ofthe fuel and can cause serious corrosion of the metal components of thegas turbine and associated structure. The vanadium cannot be removedeconomically from the fuel oil, at the present time, nor are therecommercial alloys or coatings which can be employed on the hot engineparts exposed thereto, to reliably resist its attack at elevatedtemperatures. Accordingly, at the present time various solutions to theproblem have been proposed, all of which lie in the introduction ofcertain metals or metallic compounds into the fuel and air systems forthe power plant which, during combustion, tend to combine chemically orphysically with the vanadium, thus rendering it innocuous to the gasturbine components.

One of the preferred metal elements employed as an additive is magnesiumor its compounds. These materials may be introduced in various formssuch as metallic magnesium, magnesium oxide, magnesium hydroxide,magnesium sulphate, carbonate of magnesium or even as an organiccompound of magnesium. These materials I have heretofore been addeddirectly to the fuel as aqueous solutions but, when so added, tend todeposit in the fuel lines. Oil slurries of these materials have alsobeen used but have induced severe erosion and plugging of the fuel pumpsand fuel injection nozzles. To obviate these difliculties, thesematerials, in comminuted form, have been added to combustion air inboiler installations utilizing residual fuel oil. However, this is noteasily done with gas turbines.

Although these materials are effective in inhibiting the formation ofthe harmful vanadates, they do have one serious disadvantage. They tendto be deposit forming and rapidly build up a thick coating on theturbine blades, causing the blades to lose their optimum airfoil shapeand causing the machine to operate at lower efiiciency, often timeswithin a few hours of steady operation.

It has been found that when a second material such asaluminum or one ofits compounds is employed as an additive and fed concomitantly withmagnesium materials into the plant, the combination of the aluminum andmagnesium materials tends to prevent or at least minimize theaccumulation of deposits on the turbine blades and I at otherhotcomponents. Accordingly, it is an object of the inveniton to providetwo materials as additives for residual oil fuel fired gas turbine powerplants, wherein one of the materials serves to inhibit the formation ofharmful vanadium, sodium and sulphur compounds, and the other materialiseffective to. minimize the accumulation or deposition of thesecompounds on the turbine components.

It has further been found, that in order to be eifective, theproportions of the two materials must be relatively Patented ot. 3, i951closely held and, further, the quantity of the materials fed must bevaried with fuel pressure and/or fuel flow of the specific fuelemployed, temperature within the power plant, speed of the rotor andother variables. Accordingly, it is a further object of the invention toprovide apparatus for feeding two materials of the above typeconcomitantly into the fuel combustion chamber of a gas turbine powerplant in preselected proportions and at a rate varying directly withplant operating variables.

Ordinarly, when a material such as magnesium or its compounds is usedalone, a 3/1 atom ratio of magnesium to vanadium has been foundsufiicient. However, when a second material such as aluminum or itscompounds is employed in conjunction With the magnesium materials, a 6/3/ 1 atom ratio of magnesium and aluminum to vanadium, respectively,appears to be essential. Although the mechanism by which the aluminum isrendered effective to complement the effects of the magnesium has notbeen definitely established, it appears that the aluminum materialdiverts some of the magnesium by forming a magnesium aluminatetherewith, so that more magnesium must be added to be available tocombine with the vanadium. However, this aluminate has a higher meltingtemperature and seems to be much less adherent to the blade componentsthan the usual compounds of magnesium such as the vanadates andsulphates.

It appears that the vanadates, chiefly sodium pyrovanadate and sodiumorthovanadate formed in the residual oil fuel ash is deposited on theblades in molten and high viscous form and acts as a flux, removing theprotective oxides from the blades and destroying their corrosionresistance, as well as providing oxygent for continuing corrosion.

The magnesium material, when employed alone, will substantially minimizethe above phenomenon by forming a protective coating about the blades.However, this coating builds up during operation of the machine, asmentioned above, until the efficiency of the power plant drops toeconomically unendurable values. In accordance with the invention, thealuminum permits the magnesium to act in the same manner but is highlyeffective to control the thickness, of the coating formed by themagnesium to a reasonable value.

In accordance with the invention, to insure that the magnesium andaluminum materials are fed in proper quantities to suit all operatingconditions of the power plant, the two materials are combined in acomposite rod, such as a tube made of one material and filled with theother material, and fed by a suitable variable speed mechanism directlyinto the fuel combustion chamber of the gas turbine power plant. Thecomposite rod may be stored on a reel and fed by suitable sheaves drivenby a variable speed driving mechanism, the speed of which is controlledby an integrating controller responsive to engine operating variablessuch as fuel pressure, turbine inlet temperature, etc. Accordingly, withincreasing fuel pressure, indicative of increasing fuel flow to thecombustor, the variable speed driving mechanism is effective through itscontroller to feed the composite rod into the fuel combustor at anincreasing rate. Conversely, when the fuel pressure is lowered, thecomposite rod is fed into the combustor at a lower rate. In a similarmanner, the speed of the composite rod may be increased or decreased inaccordance with increase or decrease, respec-- tively, of thetemperature adjacent the turbine inlet.

If tubing is used, the tubular sheath may be formed of aluminum andfilled with one of the magnesium compounds such as magnesium oxide, theproper proportions of magnesium oxide to aluminum being arrived at byforming the sheath of the required wall thickness and diameter.

On the other hand, various modifications of this at rangement may beemployed, to dispense with the sheath, by forming a composite rod orstrip of magnesium and aluminum bonded to each other to form abimetallic structure, or the rod may be formed of any suitable magnesiumand aluminum alloys; It may" also be feasible to form the composite rodof comminuted magnesium and aluminum materials bonded together by asuitable plastic binder.

Although magnesium and aluminum materials have been heretofore mentionedfor clarity and simplicity, the magnesium materials may be substitutedby other elements of the same chemical group, as follows: beryllium,calcium, barium, strontium, and zinc. On the other hand, the aluminummaterials may be substituted by other elements having the same chemicalcharacteristics, such as: chromium, iron, manganese, silicon, boron, titanium, zirconium, molybdenum, and tungsten.

The foregoing and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application; inwhich:

FIG. 1 is a schematic view illustrating a typical industrial gas turbinepower plant having the invention incorporated therein;

FIG. 2 is a transverse section of the tubular structure taken on lineIIII of FIG. 1; and

FIGS. 3, 4 and 5 are sections similar to FIG. 2 but illustratingdifferent modifications of the invention.

Referring to the drawing in detail, in FIG. 1 there is shown a typicalgas turbine power plant incorporating a compressor section 11 having abladed rotor 12, a gas turbine section 13 including a bladed rotor 14drivingly connected to the compressor rotor 12 by a shaft 15 and havinginterposed therebetween fuel combustion apparatus 16. The power plant 10is provided with housing structure 17 enclosing the above recitedcomponents and having an opening 13 through which a drive shaft 19 isextended for providing shaft power to an external load (not shown). Aswell known in the art, the shaft 19 is connected to the rotor aggregate12, 14 and 15 and driven thereby.

The combustion apparatus 16 includes an annular array of apertured fuelcombustion chambers 21 disposed within a plenum chamber 22 formed in thehousing structure 17 and communicating with the outlet 23 of thecompressor. Since the fuel combustion chambers 21 may be identical, onlyone has been shown and will be described.

The fuel combustion chamber 21 is of cannister form and is provided atits upstream end wall portion with a fuel injection nozzle 25 to whichfuel is fed from a suitable fuel supply 26 containing residual fuel oilthrough a conduit 27, by a fuel pump ZS-and regulated by a suitable fuelcontrol 29. The fuel control may be regulated as required to vary thefuel flow rate to an annular fuel manifold 30 connected to the nozzles25- by branch conduits 31.

The turbine section 13 is further provided with an inlet 33communicating with the fuel combustion chambers 21 and an outlet 34communicating with an exhaust outlet conduit 35.

As thus far described, the power plant 10 is substantially conventionaland operates in substantially the following manner. As residual fuel oilfrom the fuel supply 26 is delivered, as required, by the fuel control2% to the fuel combustion chambers 21 through the fuel injecting nozzles25 and ignited by suitable means (not shown), air is induced through anair intake 36 by the compressor 11 and pressurized, and thence deliveredthrough the compressor outlet 23 into the plenum chamber 22. The thuspressurized air enters the fuel combustion chambers 21, where itcombines with the atomized fuel oil being admitted thereto by the fuelnozzles 25 to sustain combustion. The resulting hot gaseous products ofcombustion are directed through the downstream ends of the fuelcombustion chambers-21 and through the turbine inlet 33 tothe turbinesection 13-, thereby motivating the turbine rotor 14. The turbine rotor14 rotates the shaft 15 and compressor rotor 12. The thus expandedmotive gases are exhausted through the turbine outlet 34 and thencethrough the exhaust outlet conduit 35,. as indicated by the arrows,. toany region. of lower pressure, such as atmospheric.

In accordance with the invention, the housing 1.7' isprovided with agenerally frusto-conical combustion. section housing portion 37 having aplurality of. apertures 38 formed therein communicating with apertures39 (only one shown) formed in each of the fuel: combustion chambers 21.As shown in FIG. 1, a composite rod such as a tubular sheathed structure40 is fed through the apertures 38 and 39 into the fuel combustion zone41 within the fuel combustion chamber 21.

The tubular structure 40' may be formedin' long continuous lengths,stored upon a rotatably mounted reel 42 and having its free endportionpassing through a pair of rollers or sheaves 43 and 44. The sheave 44 isrotatably connected to the drive shaft 45 of variable speed drivemechanism 46 rotatable in the direction indicated by the arrow to feedthe tubular sheath structure 4% into'the fuel combustion chamber 21.

The speed of the variable speed drive mechanism 46 is controlled by asuitable integrating controller 47, responsive to fuel pressure from thefuel control 29, admitted thereto by a conduit 48, and to thetemperature of the turbine inlet 33 as sensed by a thermocouple 49disposed at the downstream end of the combustion chamber 21 andconnected to the controller 47.

Referring to FIG. 2, the tubular sheath structure 40 comprises ametallic sheath 51 within which is disposed a compacted comminutedmetallic material or compound 52. The sheath 4'0 and the material 52disposed therewithin may be formed of any two of the materials selectedfrom eachof the following two groups:

Group I Aluminum Boron Chromium Titanium" Iron Zirconium ManganeseMolybdenum Silicon Tungsten Group II Magnesium Barium BerylliumStrontium. Calcium Zinc It will be understood thatthe sheath: 51 ispreferably formed of the selected metal while the material 52 disposedwithin the sheath may be formed by comminuting the selected metal oremploying. the oxide, sulphate, carbonate, chloride or hydroxideof themetal.

When the materials selected from groups I and II are aluminum andmagnesium, a 6/3/1 atom ratio of magnesium, aluminum and vanadium. hasbeen found to be adequate. Accordingly, to fulfill these requirements,aluminum tubing having an outside diameter of inch, 4 inch or inch, withacorresponding Wall thickness of .011 inch, .021 inch. and .032 inch,could be employed, for example.

A representative 5000 kw. gas turbine power plant, having six fuelcombustion chambers 21, operating atfull load and utilizing 833 lbs. percombustion chamber per hour of a residual fuel oil having 400- p.p .m.vanadium, would require about .529 lb. per hour of aluminum and 1.569lbs. per hour of magnesium oxide for: each combustion chamber. Theoptimum linear feed rate for a A; inch tube would be about 24 inches perminute per fuel combustion chamber or a total of 144' inches of tubingper minute. On the other hand, if inch tubing were employed, about 2.65inches per minute per combustion chamber or a total of 1519 inches perminute would be required. Similar calculations could be made for othertypes of materials employed.

In FIG. 3 there is shown a composite rod 53 formed of alloys ofmaterials selected from groups I and II and formed into a solid mass,thereby dispensing with the need for providing a sheath and filling thesame with comminuted material.

In FIG. 4, another variation is shown wherein the materials selectedfrom the two groups above may be bonded to each other to form acomposite rod in the form of a bimetallic strip 54 having one portion 55formed of one material and the other portion 56 of the other material.

In FIG. 5, a further embodiment is shown wherein a composite rod 57 isformed of comminuted materials selected from groups I and II in properproportion and bonded to each other by a suitable binding agent, such asone of the plastic resins.

During operation, as fuel is admitted into the combustion chamber 21 bythe fuel injecting nozzle 25, the sheath structure 40 is fed thereintoby the variable speed drive mechanism 46 at a rate determined by thefuel pressure in the fuel control 29 and the temperature of the gases atthe turbine inlet 33 and integrated in the integrating controller 47which has been preset for a range corresponding to the vanadium contentof the fuel. Accordingly, since the rate of feed of the sheath structure40 is thus regulated, the proper amount of additive for any variablecondition of operation of the power plant is thus insured.

Although the integrated controller 47 has been illustrated and describedas being controlled by fuel pressure and turbine inlet temperature, itis within the scope of the invention to control this controller inresponse to other engine operating variables such as r.p.m. of the shaft19, compressor pressure, etc.

As the sheath structure 40 is fed into the fuel combustion chamber 21,it is consumed in the fuel combustion process and modifies the hotproducts of combustion formed in such a manner that the usual anddeleterious compounds of vanadium, sodium, and sulphur are inhibited.The magnesium is thus rendered effective to provide a protective coatingabout the blading and associated components of the turbine section 13,thereby minimizing the corrosive effectiveness of the hot motive gasesof combustion. Concomitantly therewith, the aluminum is combined withsome of the magnesium to form magnesium aluminate. This aluminate isefiective to control the accumulation thickness of the protectivecoating formed by the magnesium to the minimum thickness required toprevent corrosive attack by the hot products of combustion andpreventing excessive buildup or formation of this protective coating,thereby enabling the turbine section to operate at substantially highaerodynamic efiiciency.

It will now be seen that, with the invention, clogging or erosion of thefuel system components by the admis sion of additives thereto isobviated. Also, the mixing in special tanks of slurries for feeding theadditives directly to the residual fuel oil is obviated. In additionthereto, the rate at which the additives are injected is positivelycontrolled, as required for optimum plant operation, and isautomatically modified continuously a required. Since the additives areadmitted directly into the fuel combustion chamber, settling, sludging,agglomeration and pre-reaction with the fuel in the fuel conduits isobviated.

Although the feeding apparatus for providing the additive materials hasbeen shown in conjunction with only one fuel combusion chamber 21, itwill be understood that if a plurality of such combustion chambers areemployed, the remaining fuel combustion chambers may be fed by similarapparatus through their associated apertures 38. Although each may beprovided with separate controllers and engine variable sensing means, ifdesired,

6 all of the feeding apparatus may be controlled by one set of engineoperating sensing devices.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit thereof.

What is claimed is:

l. Agas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metalcomponents subject to corrosion attack by compounds of vanadium, sodiumand sulphur, means for injecting a petroleum fuel containing one or moreof the above compound forming elements into said combustion chamber forcombustion purposes, a coil of composite rod containinga-t least twomaterials in preselected proportions, one of said materials beingeffective to inhibit the formation of at least one of the abovecompounds and forming another compound and the other of said amterialsbeing effective to minimize the deposition of said another compound onsaid turbine components, means for feeding said rod directly into saidcombustion chamber, and means for controlling said feeding means inaccordance with an operating condition of said power plant.

2. A gas turbine power plant comprising an air compressor, a fuelcombusion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metalcomponents subject to corrosion attack by compounds of vanadium, meansfor injecting a petroleum fuel containing vanadium into said combustionchamber for combustion purposes, a coil of tubing containing at leasttwo materials in preselected proportions, one of said materials beingeffective to inhibit the formation of said vanadium compounds andforming another compound and the other of said materials being effectiveto minimize the deposition of said another compound on said turbinecomponents, a variable speed drive mechanism for feeding said tubingdirectly into said combustion chamber at a variable rate, and means forcontrolling said variable speed drive mechanism in accordance with avariable operating condition of said power plant, said one materialforming said tubing and said other material being comminuted andcontained in said tubing.

3. A gas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metalcomponents subject to corrosion attack by compounds of vanadium, sodiumand sulphur, means for injecting a petroleum fuel containing one or moreof the above compound forming elements into said combustion chamber forcombustion purposes, a coil of composite rod containing at least twomaterials in preselected proportions, one of said materials beingeifective to inhibit the formation of at least one of the abovecompounds and forming another compound and the other of said materialsbeing effective to minimize the deposition of said another compound onsaid turbine components, means including a variable speed drivemechanism and sheave structure for feeding said rod directly into saidcombustion chamber at a variable rate, and a controller for controllingsaid variable speed drive mechanism in accordance with a variableoperating condition of said power plant.

4. A gas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metal bladingelements subject to corrosion attack by compounds of vanadium, sodiumand sulphur, means including a fuel control for controlling the rate ofinjection of a petroleum fuel containing vanadium, and sodium or sulphurinto said combustion chamber for combustion, a coil of composite rodcontaining magnesium and aluminum in preselected proportions, and meansfor feeding said rod into said combustion chamber at a rate sufficientto minimize formation of said compounds on said gas turbine blading.

5. A gas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metal bladesand associated components subject to corrosion attack by compounds ofvanadium, means including a ,fuel control for controlling the rate ofinjection. of a petroleum fuel containing vanadium into said combustionchamber for combustion, a coil of tubular sheathing containing magnesiumand aluminum, and variable speed mechanism for feeding said tubularsheathing into said combustion chamber for consumption at a ratesufficient to inhibit formation of said vanadium compounds and minimizeaccumulation of deposits on said gas turbine blades and components, saidsheathing being formed of said aluminum and said magnesium beingcomminuted and disposed in said sheathing.

6. A gas turbine power plant comprising an air compressor, a fullcombustion chamber and a gas turbine driven by the gaseous products ofcombustion formed in said chamber, said gas turbine having metalcomponents subject to corrosion attack by compounds of vanadium, sodiumand sulphur, mean including a fuel control for controlling the rate ofinjection of a petroleum fuel containing vanadium, and sodium or sulphurinto said combustion chamber for combustion, a composite rod containingtwo materials in preselected proportions, one of said materials beingselected from the group comprising aluminum, chromium, iron, manganese,silicon, boron, titanium, zirconium, molybdenum and tungsten, and theother of said materials being selected from the group comprisingmagnesium, beryllium, calcium, barium, strontium and zinc, and means forfeeding said rod into said combustion chamber for consumption at a ratesulficient to inhibit formation of said compounds and minimizeaccumulation of deposits on said gas turbine components.

7. A gas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the hot gaseous productsof combustion formed in said combustion chamber; said power plant havingmetal components subject to corrosion attack by com- 8 pounds ofvanadium, a supply of petroleum fuel containing vanadium, meansincluding a fuel control for controlling the rate of injection of saidfuel into said combustion chamber for combustion, a coil of tubularsheathed structure including a metallic tubular sheath having acomminuted material disposed therein, said sheathed structure beingconsumable in said combustion chamber to inhibit formation of saidvanadium compounds and minimize accumulation of deposits on said metalcomponents, means including a variable speed drive mechanism for feedingsaid sheathed structure into said combustion chamber at a variable rate,and an integrating controller responsive to at least one power plantoperating characteristic for controlling the speed of said variablespeed drive mechanism.v

8. A gas turbine power plant comprising an air compressor, a fuelcombustion chamber and a gas turbine driven by the hot gaseous productsof combustion formed in said combustion chamber; said power plant havingmetal components subject to corrosion attack by compounds of vanadium, asupply of petroleum fuel containing vanadium, means including a fuelcontrol for controlling the rate of injection of said fuel into saidcombustion chamber for combustion, a coil of tubular sheathed structureincluding a tubular sheath formed of material selected from one groupand having a comminuted material containing material selected fromanother group disposed therein, said groups comprising: aluminum,chromium, iron, manganese, silicon, boron, titanium, zirconium,molybdenum and tungsten; and magnesium, beryllium, calcium, barium,strontium and zinc; means including a variable speed drive mechanism forfeeding said sheathed structure into said combustion chamber at avariable rate, and an integrating controller responsive to at least onepower plant operating characteristic for controlling the speed of saidvariable speed drive mechanism.

References ited in the file of this patent UNITED STATES PATENTS2,399,680 Keefer May 7, 1946 2,781,005 Taylor et al Feb. 12, 1957 72,844,112 Muller July 22, 1958' 2,890,108 Toulmin June 9, 1959 FOREIGNPATENTS 1,102,480 Canada May 11, 1955 576,888 France June 2, 1959

1. A GAS TURBINE POWER PLANT COMPRISING AN AIR COMPRESSOR, A FUELCOMBUSTION CHAMBER AND A GAS TURBINE DRIVEN BY THE GASEOUS PRODUCTS OFCOMBUSTION FORMED IN SAID CHAMBER, SAID GAS TURBINE HAVING METALCOMPONENTS SUBJECT TO CORROSION ATTACK BY COMPOUNDS OF VANADIUM, SODIUMAND SULPHUR, MEANS FOR INJECTING A PETROLEUM FUEL CONTAINING ONE OR MOREOF THE ABOVE COMPOUND FORMING ELEMENTS INTO SAID COMBUSTION CHAMBER FORCOMBUSTION PURPOSES, A COIL OF COMPOSITE ROD CONTAINING AT LEAST TWOMATERIALS IN PRESELECTED PROPORTIONS, ONE OF SAID MATERIALS BEINGEFFECTIVE TO INHIBIT THE FORMATION OF AT LEAST ONE OF THE ABOVECOMPOUNDS AND FORMING ANOTHER COMPOUND AND THE OTHER OF SAID MATERIALSBEING EFFECTIVE TO MINIMIZE THE DEPOSITION OF SAID ANOTHER COMPOUND ONSAID TURBINE COMPONENTS, MEANS FOR FEEDING SAID ROD DIRECTLY INTO SAIDCOMBUSTION CHAMBER, AND MEANS FOR CONTROLLING SAID FEEDING MEANS INACCORDANCE WITH AN OPERATING CONDITION OF SAID POWER PLANT.